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Abstract:

A method for producing 1,1,1,2-tetrafluoropropene and/or
1,1,1,2,3-pentafluoropropene using a single set of four unit operations,
the unit operations being (1) hydrogenation of a starting material
comprising hexafluoropropene and optionally recycled
1,1,1,2,3-pentafluoropropene; (2) separation of the desired intermediate
hydrofluoroalkane, such as 1,1,1,2,3,3-hexafluoropropane and/or
1,1,1,2,3-pentafluoropropane; (3) dehydrofluorination of the intermediate
hydrofluoroalkane to produce the desired 1,1,1,2-tetrafluoropropene
and/or 1,1,1,2,3-pentafluoropropene, followed by another separation to
isolate the desired product and, optionally, recycle of the
1,1,1,2,3-pentafluoropropene.

Claims:

1-17. (canceled)

18. A system for producing at least one fluorinated olefin comprising: a.
a hydrogenation reactor; b. a starting material feed stream fluidly
connected to said hydrogenation reactor, wherein said starting material
feed stream comprises hexafluoropropylene; c. one or more intermediate
streams fluidly connected to said hydrogenation reactor; d. a first
separator fluidly connected to said one or more intermediate streams; e.
one or more post separator streams fluidly connected to said first
separator; f. optionally, a first recycle stream fluidly connected to
said first separator and said hydrogenation reactor; g. a
dehydrohalogenation reactor fluidly connected to at least one of said
post separator streams; h. a product stream fluidly connected to said
dehydrohalogenation reactor; i. a second separator fluidly connected to
said product stream; j. a second recycle stream fluidly connected to said
second separator and said hydrogenation reactor; and k. a final product
stream fluidly connected to said second separator, wherein said final
product stream is rich in 1,1,1,2-tetrafluoropropene or
1,1,1,2,3-pentafluoropropene.

19. The system of claim 18 wherein said final product stream is rich in
1,1,1,2-tetrafluoropropene and said second recycle stream is rich in said
1,1,1,2,3-pentafluoropropene.

[0002] Fluorinated olefins, as a class, have many and varied uses,
including as chemical intermediates and monomers, refrigerants, blowing
agents, propellants and solvents.

[0003] Several methods for preparing fluorinated olefins are known. For
example, U.S. Pat. No. 5,679,875 discloses methods for manufacturing
1,1,1,2,3-pentafluoropropene and 1,1,1,2,3-pentafluoropropane; U.S. Pat.
No. 6,031,141 discloses a catalytic process using chromium-containing
catalysts for the dehydrofluorination of hydrofluorocarbons to
fluoroolefins; U.S. Pat. No. 5,396,000 discloses a process for producing
CF3CHFCH2F using vapor phase catalytic dehydrohalogenation to produce
CF3CF═CHF and HF, followed by vapor phase catalytic hydrogenation of
CF3CF═CHF in the presence of HF; U.S. Pat. No. 6,548,719 discloses a
process for producing fluoroolefins by dehydrohalogenating a
hydrofluorocarbon in the presence of a phase transfer catalyst; U.S.
Publication No. 2006/0106263 discloses the production and purification of
hydrofluoroolefins compounds; and WO98/33755 discloses catalytic process
for the dehydrofluorination of hexafluoropropanes to pentafluoropropenes.

[0004] Applicants have also come to appreciate that
1,1,1,2,3-pentafluropropene (HFO-1225ye) and 1,1,1,2-tetrafluoropropene
(HFO-1234yf) are each useful in various application, and in certain
application, one of the compounds might be favored over the other. For
example, HFO-1234yf is more preferred than HFO-1225ye for certain
refrigerant and blowing agent applications.

[0005] Applicants have previously developed a process for producing
HFO-1234yf which involves hydrogenating HFO-1225ye to produce
1,1,1,2,3-pentafluropropane (HFC-245eb) and then using the HFC-245eb as a
reactant in a dehydrofluorination reaction to produce HFO-1234ye.
Applicants have also previously developed a process for producing
HFO-1225ye which involves first hydrogenating hexafluoropropylene (HFP)
to produce 1,1,1,2,3,3-hexafluropropane (HFC-236ea) and then using the
HFC-236ea as a reactant in a dehydrogenation reaction to produce
HFO-1225ye. To commercially produce these two products according to these
prior art processes, a manufacturing facility would require a minimum of
four separate unit operations for each product, i.e., hydrogenation of
the starting material, separation of the desired intermediate,
dehydrofluorination of the intermediate to produce the desired product,
followed by another separation to isolate the desired product. Applicants
have come to appreciate that substantial economic investment would be
required to develop such a commercial facility. As a result, it might
become economically prohibitive to build a processing facility to produce
each of these desirable fluorinated olefins according to the prior art
processes.

[0006] In view of applicants' recognition of the above-noted problems and
features of prior processes, applicants have developed improved processes
that are capable of achieving substantial economic advantage in capital
cost as well as substantial flexibility and advantage in the actual
operation to maximize efficiency and production of a range of fluorinated
olefins.

SUMMARY OF THE INVENTION

[0007] Applicants have found that both HFO-1225ye and HFO-1234yf can be
produced in a single facility having four unit operations. The present
invention, in part, is the recognition that hydrogenation of HFP with
hydrogen yields both HFC-236ea and HFC-245eb. (It is believed that the
HFC-245eb forms from the reaction of HFC-236ea with H2.) Like
HFC-236ea, HFC-245eb subsequently can be dehydrofluorinated to produce a
desirable product. In particular, HFC-236ea can be dehydrofluorinated to
produce HFO-1225ye and HFC-245eb can be dehydrofluorinated to produce
HFO-1234yf. Thus, both HFO-1225ye and HFO-1234yf can be produced using a
single set of four unit operations: hydrogenation of the starting
material, separation of the desired intermediate, dehydrofluorination of
the intermediate to produce the desired product, followed by another
separation to isolate the desired product. For example, in a preferred
system, HFP and H2 are reacted in a hydrogenation reactor to form an
intermediate product stream comprising HFC-236ea and/or HFC-245eb. The
relative concentrations of HFC-236ea and HFC-245eb is dependant on
reaction conditions in the hydrogenation reactor, such as pressure,
temperature, and relative concentration of reactants in the reactor. If
the desirable end product is HFO-1225ye, then processing conditions
preferably favor the production of HFC-236ea. That is, the hydrogenation
reactor is operated to produce an intermediate product stream rich in
HFC-236ea which is subsequently separated from the intermediate process
stream and fed into a dehydrofluorination reactor to form a final product
stream comprising HFO-1225ye. This HFO-1225ye is then separated from the
final product stream and recovered as a purified product. If the
desirable end product is HFO-1234yf, then processing conditions
preferably favor the production of HFC-245eb. That is, the hydrogenation
reactor is operated to produce an intermediate product stream rich in
HFC-245eb. This can be accomplished by operating the hydrogenation
reactor under conditions favorable to convert the HFP into HFC-236ea and
then converting the HFC-236ea into HFC-245eb. The HFC-245eb is then
separated from the intermediate product stream and fed into a
dehydrofluorination reactor to form a final product stream comprising
HFO-1234yf. This HFO-1234yf is then separated from the final product
stream and recovered as a purified product.

[0008] In addition, when HFO-1234yf is the desired product, HFO-1225ye can
be introduced into the hydrogenation reactor at some point and then
converted into HFC-245eb. The source of this HFO-1225ye can be either a
separate feed stream and/or a recycle stream (i.e., recycling HFO-1225ye
derived from HFC-236ea as noted above). The HFC-245eb is again separated
from the intermediate product stream and fed into a dehydrofluorination
reactor to form a final product stream comprising HFO-1234yf. This
HFO-1234yf is then separated from the final product stream and recovered
as a purified product.

[0009] The discovery that both HFO-1225ye and HFO-1234yf can be produced
using the same processing equipment is of great economic advantage.
Accordingly, the present invention provides in one aspect methods of
producing fluorinated olefins, preferably fluorinated olefins having from
3 to 6 carbon atoms and at least 4 fluorine substituents, and even more
preferably at least one fluorinated olefin selected from the group
consisting of 1,1,1,2-tetrafluoropropene (HFO-1234yf),
1,1,1,2,3-pentafluoropropene (HFO-1225ye) and combinations of these. The
methods preferably comprise: hydrogenating at least one highly
fluorinated olefin, preferably a fluorinated propene having a degree of
fluorination of N+1, and even more preferably at least five fluorine
substituents (i.e., N=4 or greater), and even more preferably HFP, to
produce one or more fluorinated alkanes, preferably one or more
fluorinated propanes having a degree of fluorination of N+1, even more
preferably HFC-236ea and/or HFC-245eb; and dehydrofluorinating the
fluorinated alkane(s) to produce a crude product stream comprising one or
more of the desired fluorinated olefins having a degree of fluorination
of N, preferably HFO-1234yf and/or HFO-1225ye. In preferred applications,
these methods further comprise the step of providing a separation system
capable of separating from the crude product stream a first desired
fluorinated olefin and further providing at least a first and a second
alternative flow path for said first fluorinated olefin, said first flow
path being adapted to introduce (e.g., recycle) at least a portion of
said first fluorinated olefin into said hydrogenation reaction step and
said second flow path being adapted to deliver said first desired
fluoroolefin to further processing to produce a relatively refined
product stream containing said first desired fluoroolefin, said first and
second alternate flow paths being operable independently.

[0010] Referring to FIG. 10, another aspect of the present invention
provides systems capable of simultaneously and alternatively producing
1,1,1,2-tetrafluoropropene (HFO-1234yf) and 1,1,1,2,3-pentafluoropropene
(HFO-1225ye) comprising: (a) at least a first hydrogenation reactor
adapted to be operated under conditions effective to convert a feed
stream comprising HFP, and optionally or alternatively HFO-1225ye, into
at least one hydrogenation reaction product stream comprising a major
proportion of HFC-236ea or a major proportion of HFC-245eb (based on the
total amount of HFC-236ea and HFC-245eb in the hydrogenation reaction
product stream); (b) at least a first separator capable of separating
said hydrogenation reactor product stream into a plurality of streams,
wherein at least one of said streams (i.e., a first intermediate stream)
is relatively rich in either HFC-236ea or HFC-245eb and, optionally,
another stream (i.e., a second intermediate stream) relatively rich in
the other; (c) at least one dehydrofluorination reactor adapted to be
operated under conditions effective to convert at least a portion of the
hydrogenation reaction product separated into said first and/or second
intermediate streams into at least one of 1,1,1,2-tetrafluoropropene
(HFO-1234yf), 1,1,1,2,3-pentafluoropropene (HFO-1225ye), and combinations
of these. In preferred embodiments, the systems further comprise: (d) at
least a second separator capable of separating dehydrofluorination
reaction product into at least a first product stream relatively rich in
HFO-1234yf and/or at least a second product stream relatively rich in
HFO-1225ye. In certain preferred embodiments the systems include a flow
path for recycling at least a portion, and preferably all, of the stream
rich in HFO-1225ye to the hydrogenation reactor and a flow path. In
certain preferred embodiments, the systems include at least a second flow
path operable simultaneously and independently of said first flow path to
deliver said HFO-1225ye to further processing to produce a relatively
refined product stream containing relatively higher concentrations of
HFO-1225ye.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a process flow diagram showing the production of
fluoroolefins according to an embodiment of the invention.

[0012] FIG. 2 is a process flow diagram showing the hydrogenation unit
operation according to an embodiment of the invention.

[0013]FIG. 3 is a process flow diagram showing the hydrogenation unit
operation according to another embodiment of the invention.

[0014] FIG. 4 is a process flow diagram showing the first separation unit
operation according to an embodiment of the invention.

[0015] FIG. 5 is a process flow diagram showing the first separation unit
operation according to another embodiment of the invention.

[0016]FIG. 6 is a process flow diagram showing the dehydrofluorination
unit operation according to an embodiment of the invention.

[0017]FIG. 7 is a process flow diagram showing the dehydrofluorination
unit operation according to another embodiment of the invention.

[0018] FIG. 8 is a process flow diagram showing the second separation unit
operation according to an embodiment of the invention.

[0019] FIG. 9 is a process flow diagram showing the second separation unit
operation according to another embodiment of the invention.

[0020] FIG. 10 is a process flow diagram showing the production of
different fluoroolefins using the same four unit operations according to
certain embodiments of the invention.

DETAILED DESCRIPTION

[0021] In certain highly preferred embodiments, the desired fluorinated
olefins of the present invention comprise one or more C3 to C6
fluoroalkenes, preferably compounds having a formula as follows:

X1CFzR3-z

where X1 is a C2, C3, C4, or C5 unsaturated, substituted or
unsubstituted, alkyl radical, each R is independently Cl, F, Br, I or H,
and z is 1 to 3. Highly preferred among such compounds are propenes and
butenes having from 3 to 5 fluorine substituents, and among these
tetrafluoropropenes (HFO-1234) and pentafluoropropenes (HFO-1225) are
especially preferred.

[0022] Preferred processes of the present invention comprise reacting a
fluorinated olefin starting material with a degree of halogen
substitution of N+1 having substantially the same number of carbon atoms
as the fluorinated olefin(s) to be synthesized with a degree of halogen
substitution of N. Preferably the fluorinated olefin starting material
having a degree of fluorine substitution of N+1 is exposed to reaction
conditions effective to produce a reaction product containing one or more
fluorinated alkanes having the same number of carbons atoms as the
olefin. In one preferred aspect of the present invention, this olefin
conversion step comprises a reaction that is sometimes referred to herein
for convenience, but not necessarily by way of limitation, as a reduction
or hydrogenation step. The fluorinated alkane is then preferably
converted to a fluorinated olefin having a degree of fluorine
substitution of N. In one preferred aspect of the present invention, this
alkane conversion step comprises a reaction that is sometimes referred to
herein for convenience, but not necessarily by way of limitation, as a
dehydrohalogenation reaction or more particularly in certain embodiments
as a dehydrofluorination or dehydrochlorination reaction.

[0023] According to one aspect of the present invention, the present
processes preferably comprise the steps of [0024] (a) hydrogenating a
compound of formula (I)

[0024] (CXnY3-n)(CR1aR2b)zCX═CH.s-
ub.mX2-m (I)

under conditions effective to form at least one fluorinated alkane of
formula (II)

(CXnY3-n)(CR1aR2b)zCHXCHm+1X.sub-
.2-m (II)

where: [0025] each X is independently Cl, F, I or Br, provided that at
least two Xs are F; [0026] each Y is independently H, Cl, F, I or Br;
[0027] each R1 is independently H, Cl, F, I, Br or unsubstituted or
halogen substituted methyl or ethyl radical; [0028] each R2 is
independently H, Cl, F, I, Br or unsubstituted or halogen substituted
methyl or ethyl radical; [0029] n is 1, 2 or 3 (preferably 3); [0030] a
and b are each 0, 1 or 2, provided that a+b=2; [0031] m is 0, 1 or 2
(preferably 0 or 1); and [0032] z is 0, 1, 2 or 3 (preferably 0), and
[0033] (b) deydrohalogenating the compound of formula (II) under
conditions effective to produce a fluoroolefin with a lower degree of
fluorine substitution than the compound of formula (I), preferably to
produce a compound of formula (III):

[0033] (CXnY3-n)(CR1aR2b)ZCX═CH.s-
ub.m+1X1-m (III)

where each n is the same value as in formula (I) and m is 0 or 1.

[0034] In certain preferred embodiments, the reactant of formula (I)
comprises a three carbon olefin of formula (IA) wherein z is 0, namely

CXnY3-nCX═CHmX2-m (IA)

to produce a three carbon alkane of formula (IIA) as follows:

(CXnY3-n)CHXCHm+1X2-m (IIA)

where X, Y, n, and m are all as indicated above, which compound is then
dehydrohalogenated to form a compound of formula (IIIA)

(CXnY3-n)CX═CHm+1X1-m (IIIA)

where n is the same value as in formula (IA) and m is 0 or 1.

[0035] In certain highly preferred aspects of such embodiments, a
saturated terminal carbon of the compounds of formulas (I) or (IA) is
fully substituted with fluorine (for example, n on the saturated terminal
carbon is 3 and each X on that carbon is F), and even more preferably n
is 3 and each X in the compound is F.

[0036] For three carbon embodiments of such preferred aspects, the
compound of Formula (IA) is preferably a fluoropropene having from three
to six fluorine substituents, and potentially other halogen substituents,
including for example hexafluoropropene (that is, Z is 0, n is 3, m is 0,
and all X are F) or pentafluoropropene (that is, Z is 0, n is 3, m is 1,
and all X are F), and the compound of formula (IIA) preferably comprises,
and more preferably is selected from the group consisting of, one or more
of the following fluorinated alkanes: chlorotrifluoropropane (HCFC-244)
and pentafluoropropane (HFC-245), and hexafluoropropane (HFC-236),
including all isomers of each of these, but preferably
1,1,1,2,3-pentafluoropropane (HFC-245eb), 1,1,1,2,3,3-hexafluoropropane
(HFC-236ea) and combinations of these. In certain preferred embodiments
the fluorinated alkane produced by the conversion step has a degree of
fluorine substitution of N+1.

[0037] In preferred embodiments, the step wherein the olefin is converted
to an alkane is carried out under conditions effective to provide a
formula (I) conversion of at least about 40%, more preferably at least
about 55%, and even more preferably at least about 70%. In certain
preferred embodiments the conversion is at least about 90%, and more
preferably about 99%. Further in certain preferred embodiments, the
conversion of the compound of formula (I) to produce a compound of
formula (II) is conducted under conditions effective to provide a formula
(II) selectivity of at least about 60%, more preferably at least about
80%, and more preferably at least about 90%, and even more preferably
about 100%.

[0038] In preferred embodiments, the step wherein the alkane is converted
to a fluorinated olefin having a degree of fluorination of N is carried
out under conditions effective to provide a formula (II) conversion of at
least about 40%, more preferably at least about 55%, and even more
preferably at least about 70%. In certain preferred embodiments the
conversion is at least about 90%, and more preferably about 95%. Further
in certain preferred embodiments, the conversion of the compound of
formula (II) to produce a compound of formula (III) is conducted under
conditions effective to provide a formula (III) selectivity of at least
about 60%, more preferably at least about 80%, and more preferably at
least about 90%, and even more preferably about 98%.

[0039] With reference now to FIG. 1, the preferred methods and systems of
the present invention comprise at least a first hydrogenation reactor A
and at least a first feed stream 1 to the hydrogenation reactor which
comprises at least one fluorinated olefin having a degree of halogen
substitution, and preferably a degree of fluorine substitution, of N+1.
The hydrogenation step A preferably involves also a feed stream 2
comprising a reducing agent. The converting step A preferably includes
providing one or more reaction vessels, at least one of which preferably
contains a reduction or hydrogenation catalyst, and introducing streams 1
and 2 into the vessel(s) under conditions effective to achieve the
desired conversion.

[0040] Although the streams 1 and 2 in the figure are shown for
convenience as being separate streams, this is done for convenience and
the present invention is not so limited. For example, the streams 1 and 2
could in certain embodiments be combined outside the vessel and then
introduced to the vessel together, or in other embodiments stream 1 and
stream 2 might each comprise several separate streams, each of which is
introduced into the vessel(s) at different times and/or at different
locations. Furthermore, the present invention contemplates, as will be
described in more detail hereinafter, that the stream 1 may actually
comprise two or more separate streams and the step A may comprise two or
more reaction vessels. All such variations are contemplated. This same
convention has been used and applies herein throughout to all use of the
term "stream," "step" and the like in both the description and in the
figures, unless specifically indicated otherwise.

[0041] The preferred converting step A produces at least one reaction
product stream 3 which contains a fluorinated alkane in accordance with
the present invention. Stream 3 is preferably introduced to a separation
step B which provides at least a first stream 5 which is used as a
reactant in the dehydrohalogenation step C. A stream or flow path 4 is
also preferably provided from separation step B for returning at least a
portion of the reaction product stream 3 to the hydrogenation reaction
step A. Stream 5, which contains at least a portion of the fluorinated
alkane reaction product form step A, is fed to the dehydrohalogenation
step C, wherein the fluorinated alkane in stream is converted to a
fluorinated olefin have a degree of halogen substitution, and in certain
preferred embodiments fluorine substitution, of N in accordance with the
present invention. The converting step C preferably includes providing
one or more reaction vessels, at least one of which preferably contains a
dehydrohalogenation catalyst and introducing at least stream 5 into the
vessel(s) under conditions effective to produce the desired fluoroolefin
in crude reaction product stream 6.

[0042] In preferred embodiments, the conversion step C produces a reaction
product which includes not only one or more of the desired fluoroolefins,
but also hydrogen and other by-products, which are withdrawn from the
reaction step C by crude product stream 6. In such embodiments it is
generally preferred to introduce the stream 6 into a separation step D in
which at least a portion of the hydrogen is separated from the stream to
produce at least a first stream 7 relatively rich (in comparison to the
crude product stream 6) in the desired fluorinated olefin, at least a
second stream relatively rich (in comparison to the feed stream 4) in
hydrogen and/or other byproducts, and at least one recycle stream 8 for
returning at least a certain portion of the unreacted reactants to the
dehydrohalogenation step C. In addition, according to preferred
embodiments, it is preferred to provide from the separation step or unit
a flow path 10 for returning at least a portion of any HFO-1225ye
contained in the crude reaction product 6 to the hydrogenation step A.

[0043] Preferred aspects of each of the steps A, B, C and D, and each of
the feed streams, product streams and flow paths associated therewith are
described below.

The Hydrogenation Step

[0044] Although it is contemplated that the hydrogenation or reduction
step may be conducted in batch operation, it is preferred that the
hydrogenation reaction is carried out as a substantially continuous
operation. Furthermore, it is contemplated that the hydrogenation
reaction may be conducted in a single reaction vessel, it is also
contemplated that reaction step A may comprise two or more reactors or
reaction stages in parallel, in series, or both, or any combination of
reactor designs. In addition, it is contemplated that the reaction step
may include one or more feed preheating steps or stages, depending on the
particulars of each application.

[0045] While it is possible that the reaction may involve in certain
embodiments a liquid phase reaction, it is contemplated that in preferred
embodiments the hydrogenation reaction comprises, and even more
preferably consists of, at least one vapor phase reaction stage.

[0046] In one preferred embodiment of the present invention, the
hydrogenation step comprises a reaction step A having associated
therewith at least a first flow path or feed stream 1A, at least a second
flow path or feed stream 1B and at least a third flow path or feed stream
2, with each flow path being independently operable. One such embodiment
is illustrated schematically in FIG. 2. In such embodiments, it is
preferred that the first flow path or feed stream 1A comprises HFP and
preferably substantially all of the HFP being fed to the reaction step A,
the second path or feed stream 1B comprises HFO-1225ye, and preferably
substantially all of the HFO-1225ye being fed to the reaction step A (it
being recognized that the feed stream 1B in many embodiments will have a
substantially zero flow and that in other embodiments this feed stream 1B
may in fact be a recycle stream from subsequent operations in the
process). The feed stream 2 comprises the hydrogenation agent, preferably
H2, for the reaction step A. Flow path or stream 4 is at path for
allowing introduction of a recycle stream into the reaction step. In some
embodiments, the actual flow of recycle stream 4 is zero, but in
preferred embodiments, the recycle stream comprises a relatively low
temperature stream comprising a portion of the reaction product stream 3A
after it has been cooled and separated, the content of recycle stream 4,
when present, preferably being relatively rich in HFC-236ea, HFC-245eb,
or a combination of these.

[0047] In another preferred embodiment of the present invention as
illustrated in FIG. 3, the hydrogenation step comprises at least a first
reaction step A1 and a second reaction step A2. The first reaction step
A1, which may comprise one or more reaction stages in parallel or in
series or a combination of parallel or series, having associated
therewith at least a first flow path or feed stream 1A and at least a
second flow path or feed stream 2A, with each flow path being
independently operable. The first reaction step A1, which may comprise
one or more reaction stages in parallel or in series or a combination of
parallel or series, having associated therewith at least a first flow
path or feed stream 1A and at least a second flow path or feed stream 2A,
with each flow path being independently operable. In such embodiments, it
is preferred that the first flow path or feed stream 1A comprises HFP and
preferably substantially all of the HFP being fed to the reaction step A,
the second path or feed stream 2B comprises the hydrogenation agent,
preferably H2, for the reaction step A. Flow path or stream 4A is at path
for allowing introduction of a recycle stream into the reaction step. In
some embodiments, the actual flow of recycle stream 4A is substantially
zero, but in preferred embodiments, the recycle stream comprises a
relatively low temperature stream comprising a portion of the reaction
product stream 3A after it has been cooled and separated, the content of
recycle stream 4, when present, preferably being relatively rich in
HFC-236ea, HFC-245eb, or a combination of these. The first reaction step
A1, which may comprise one or more reaction stages in parallel or in
series or a combination of parallel or series, having associated
therewith at least a first flow path or feed stream 1A and at least a
second flow path or feed stream 2A, with each flow path being
independently operable.

[0048] In connection with the reaction stage converting HFP in the
hydrogenation reactor, it is preferred in certain embodiments to use a
trickle bed reactor. It is contemplated that the reaction is such case
proceeds as follows:

CF3CF═CF2+H2→CF3CHFCF2H (HFC-236ea).

A major side reaction of this process yields HFC-245eb and HF. It is
believed that 245eb is formed from 236ea by hydrodefluorination and/or by
dehydrofluorination followed by reduction:

HFC-236ea+H2→HFC-245eb+HF.

[0049] The second reaction step A2, which may comprise one or more
reaction stages in parallel or in series or a combination of parallel or
series, having associated therewith at least a first flow path or feed
stream 1B and at least a second flow path or feed stream 2B, with each
flow path being independently operable. In such embodiments, it is
preferred that the first flow path or feed stream 2B, when present,
comprises HFO-1225ye, and preferably substantially all of the HFO-1225ye
being fed to the reaction step A (it being recognized that the feed
stream 2B in many embodiments will have a substantially zero flow and
that in other embodiments this feed stream 2B may in fact be a recycle
stream from subsequent operations in the process). The second path or
feed stream 2B comprises the hydrogenation agent, preferably H2, for the
reaction step A2. Flow path or stream 4B is at path for allowing
introduction of a recycle stream into the reaction step. In some
embodiments, the actual flow of recycle stream 4B is zero, but in
preferred embodiments, the recycle stream comprises a relatively low
temperature stream comprising a portion of the reaction product stream 3A
and/or 3B after it has been cooled and separated, the content of recycle
stream 4B, when present, preferably being relatively rich in HFC-236ea,
HFC-245eb, or a combination of these. Flow path or stream 10 is at path
for allowing introduction of a second recycle stream into the reaction
step, which in preferred embodiments comprises at least a portion of the
reaction product stream 6 after being processed to comprise a stream
relatively rich in HFO-1225ye.

[0050] In connection with the reaction stage converting HFO-1225ye in the
hydrogenation reactor, it is preferred in certain embodiments to use a
trickle bed reactor. It is contemplated that the reaction is such case
proceeds as follows:

CF3CF═CFH (liq)+H2 (gas)→CF3CHFCFH2
(HFC-245eb-gas)

A major side reaction is contemplated to be:

HFC-245eb+H2→CF3CHFCH3 (HFC-254)+HF

[0051] Preferably, the hydrogenation reaction conditions are controlled in
the reaction in order to achieve the desired conversion and/or
selectivity in accordance with the present invention. As used herein, the
term "reaction conditions" is intended to include the singular and means
control of any one or more processing parameters, including possibly
using or not using a reaction vessel or stage, which can be modified by
the operator of the reaction to produce the conversion and/or selectivity
of the feed material in accordance with the teachings contained herein.
By way of example, but not by way of limitation, conversion of the feed
material may be controlled or regulated by controlling or regulating any
one or more of the following: the temperature of the reaction, the flow
rate of the reactants, the presence of diluent, the amount of catalyst
present in the reaction vessel, the shape and size of the reaction
vessel, the pressure of the reaction, and any one combinations of these
and other process parameters which will be available and known to those
skilled in the art in view of the disclosure contained herein. The size
and shape, and other characteristics of the reaction vessel itself may
vary widely with the scope of the present invention, and it is
contemplated that the vessel associated with each stage may be different
than or the same as the vessel associated with the upstream and
downstream reaction stages. Furthermore, it is contemplated that all
reaction stages can occur inside a single vessel, provided that means and
mechanisms necessary to control conversion are provided. For example, it
may be desirable in certain embodiments to utilize a single tubular
reactor for each reaction stage, providing conversion control by
judicious selection of the amount and/or distribution of catalyst
throughout the tubular reactor. In such a case, it is possible to further
control the conversion in different sections of the same tubular reactor
by controlling the amount of heat removed from or added to different
sections of the tubular reactor.

[0052] Those skilled in the art will be readily able to select the type of
catalyst(s) used for the hydrogenation step of the present invention in
view of the teachings contained herein. For example, it is preferred in
certain embodiments that at least one, but preferably all, reaction
stages utilize palladium catalyst, preferably 1% palladium on carbon,
either alone or in combination with other catalysts. In this regard one
or more of the hydrogenation catalyst disclosed in U.S. Pat. No.
5,679,875, which is incorporated herein by reference, may be used for one
or more of the reaction stages in accordance with the present invention.
In certain preferred embodiments, the catalyst preferably comprises
palladium supported on carbon, such as a carbon mesh.

[0053] Thus, certain embodiments of the present methods comprise bringing
a fluorinated olefin in accordance with formula I and a hydrogenation
agent, such as H2, into contact with a first amount of catalyst in
at least a first reaction stage to produce a reaction stream comprising
hydrofluorocarbon(s), unreacted fluorinated olefin and hydrogen. In
certain preferred embodiments the hydrogenation step is followed by a
preferred separation step as described below. While it is contemplated
that a wide variety of hydrogenation reaction temperatures may be used,
depending on relevant factors such as the catalyst being used and the
most desired reaction product, it is generally preferred that the
reaction temperature for the hydrogenation step is from about 50°
C. to about 150° C., preferably about from 75° C. to about
115° C., and even more preferably from about 90° C. to
about 100° C.

[0054] In general it is also contemplated that a wide variety of reaction
pressures may be used, depending again on relevant factors such as the
specific catalyst being used and the most desired reaction product. The
reaction pressure can be, for example, from about 100 psig to about 300
psig, preferably about from 150 psig to about 250 psig, and even more
preferably about 200 psig.

[0055] Applicants have found, without being bound by or to any particular
theory, that the use of a cooled recycle stream 4 in the hydrogenation
reaction allows the feed materials to serve as a means for removing heat
from the hydrogenation reaction. Since the reduction or hydrogenation
reaction of the present invention is generally exothermic, and usually
substantially exothermic, the use of such a recycle material has the
effect in preferred embodiments of maintaining the reactor temperature
below that which would exist if the recycle were not used, assuming all
other process conditions were maintained the same.

[0056] It is contemplated that the amount of hydrogen used may vary
widely. In preferred embodiments, the hydrogen is feed to the reaction
step as a gas in a H2:olefin feed ratio of from about 1:1 to about 2:1,
and even more preferably ratio of from about 1:1 to about 1.5:1, and even
more preferably about 1.3:1.

The Hydrogenation Reaction Effluent Separation

[0057] Thus, in certain preferred embodiments, the present invention
includes the step of cooling at least a portion reactor product stream to
remove at least a portion of the heat of reaction. In many preferred
embodiments, this cooling step is included as part of the preferred
aspects of the separation step B, which are described in connection with
FIGS. 4, 5 and 6 below. Preferably the ratio of cooled recycled reaction
product to fresh feed is about 12:1, with the temperature of the recycle
stream preferably being at about 50° C. to about 100° C.,
and even more preferably about 70° C. In addition, in order to
help remove heat of reaction, it is preferred in certain embodiments to
introduce the fresh feeds and/or the recycle feeds to the reaction in the
liquid phase and allowing the heat of reaction to evaporate the liquid
feed and/or the reaction products and withdrawing the reaction products
in the gas phase.

[0058] With reference now to FIG. 4, the reaction product streams 3A and
3B are directed to a separation step B, which comprises in the embodiment
of FIG. 4 a cooling step B1 which produces one or more cooled reaction
product streams 3AB, which in turn are fed to one or more separation
stages B2. It is contemplated that those skilled in the art will be able
to devise without undue experimentation many means and mechanisms for
attaining such cooling in view of the teachings contained herein and all
such means and mechanisms are with the scope of the present invention.
The preferred separation step B2 preferably includes at least a first
separation step which produces a first stream 4 relatively rich in
unreacted hydrogen, fluorinated alkane, such as HFC-236ea and/or
HFC-245eb, or a combination of these, which may be recycled, with or
without further processing, to the reaction step A. A second stream 5,
which is relatively rich in the fluorinated alkane, such as HFC-236ea
and/or HFC-245eb, is also produced from the separation step B2.

[0059] In one preferred embodiment shown in FIG. 4A, the separation step
comprises, in addition to the cooling step B1 and the separation step B2
which produces at least a first cooled stream 4A containing a portion of
the reaction product, which is preferably recycled to the reaction step
A, and a crude product stream 100 which is fed to a further separation
step B3 in which a substantial portion of excess hydrogen in the stream
100 is purged from the stream and sent for disposal or further processing
in stream 4B. The stream 101 from the separation step B3 is then feed to
a further separation step B4 where unwanted by-products are removed in
stream 4C and one or more product streams 5A and 5B are produced. In
preferred embodiments, stream 5A is relatively rich in a first
fluorinated alkane, preferably HFC-236ea, and a second stream 5B rich in
a second fluorinated alkane, preferably HFC-245eb.

[0060] In another embodiment described with reference now to FIG. 5, the
reaction product streams 3A and 3B are each directed to a separate
separation steps, which comprise separate cooling steps B1 and B1', each
of which produces one or more cooled reaction product streams 3A' and
3B', which in turn are fed to separate separation stages B2 and B2' to
produce a first stream 5A relatively rich in a first of the fluorinated
alkane products, such as HFC-236ea when the feed stream 3A is rich in
HFP, and a second reaction product stream 5B relatively rich in a second
of the fluorinated alkane products, such as HFC-245eb when the feed
stream 3B is rich in HFO-1225ye. A stream 4 (not shown) as described
above in connection with FIG. 4 may also be removed from each of the
steps B2 and B2'. In addition, the particular embodiments shown and
described in FIG. 4A may also be adapted for use in connection with one
or both the separation steps B and B' shown in FIG. 5.

Dehydrohalogenation

[0061] It is contemplated that the dehydrohalogenation reaction step may
be preformed using a wide variety of process parameters and process
conditions in view of the overall teachings contained herein, such as for
example it is contemplated that the dehydrohalogenation step may
comprise, in certain nonpreferred embodiments, a liquid phase reaction.
However, it is preferred in many embodiments of the present invention
that this reaction step comprise a gas phase reaction, preferably in the
presence of catalyst, preferably a metal catalyst, and even more
preferably one or more transition metal-based catalysts (including in
certain preferred embodiments transition metal halide catalysts), such as
FeCl3, chromiumoxyfluoride, Ni (including Ni mesh), NiCl2,
CrF3, and mixtures thereof, supported or in bulk. Other catalysts
include carbon-supported catalysts, antimony-based catalysts (such as
SbCl5), aluminum-based catalyst (such as AlF3, Al2O3,
and fluorinated Al2O3). It is expected that many other
catalysts may be used depending on the requirements of particular
embodiments, including for example palladium-based catalyst,
platinum-based catalysts, rhodium-based catalysts and ruthenium-based
catalysts. Of course, two or more any of these catalysts, or other
catalysts not named here, may be used in combination.

[0062] In general it is preferred that the catalysts are fluorinated. In
preferred embodiments, fluorination of the catalysts comprises exposing
the catalyst to a stream of HF at about reaction temperature and
pressure. The gas phase dehydrohalogenation reaction may be conducted,
for example, by introducing a gaseous form of a compound of formula (II)
into a suitable reaction vessel or reactor. Preferably the vessel is
comprised of materials which are resistant to corrosion such as
Hastelloy, Inconel, Monel and/or fluoropolymers linings. Preferably the
vessel contains catalyst, for example a fixed or fluid catalyst bed,
packed with a suitable dehydrohalogenation catalyst, with suitable means
to heat the reaction mixture to the desired reaction temperature.

[0063] While it is contemplated that a wide variety of reaction
temperatures may be used, depending on relevant factors such as the
catalyst being used and the most desired reaction product, it is
generally preferred that the reaction temperature for the
dehydrohalogenation step is from about 150° C. to about
600° C., preferably about from 200° C. to about 400°
C., and even more preferably from about 250° C. to about
300° C.

[0064] In general it is also contemplated that a wide variety of reaction
pressures may be used, depending again on relevant factors such as the
specific catalyst being used and the most desired reaction product. The
reaction pressure can be, for example, superatmospheric, atmospheric or
under vacuum. In certain embodiments, an inert diluent gas and/or an
oxidizing agent, such as nitrogen, oxygen and mixture of nitrogen and
oxygen, may be used in combination with the compound of formula (II) as a
feed to the dehydrohalogenation step. When such a diluent and/or
oxidizing agent is used, it is generally preferred that the feed streamed
comprise formula (II) compound in an amount of from about 5% to greater
than 95% by weight based on the combined weight of diluent and formula
(II) compound.

[0065] It is contemplated that the amount of catalyst used will vary
depending on the particular parameters present in each embodiment. In
preferred embodiments, the contact time, which is expressed as the ratio
of the volume of the catalyst (ml) to the total feed flow (ml/sec) is
from about 0.1 seconds to about 1000 seconds, and preferably from about 2
seconds to about 120 seconds.

[0066] In general it is contemplated that the reaction is endothermic. To
assist thermal management, it is contemplated in certain embodiments that
the reactor comprises an isothermal tubular reactor, with heat input
being provided by means of a relatively high temperature heating medium,
such as hot salt and/or oil, superheated steam, or re-circulating hot
gas. In addition, recycling of the HFO-1225ye produced in the reaction
may be used to help control the temperature of the reaction.

[0067] One preferred dehydrohalogenation reaction comprises a
dehydrofluorination reaction. For example, for embodiments in which the
desired product of formula (III) is HFO-1234yf, it is preferred in
certain embodiments that the compound of formula (II) comprises 1,1,1,2,3
pentafluoropropane. Applicants have found that in such embodiments it is
preferred to use as the catalyst a fluorinated chromium oxide catalyst.

[0068] Preferably in such dehydrofluorination embodiments, the conversion
is at least about 50%, more preferably at least about 65%, and even more
preferably at least about 90%. Preferably, the selectivity to HFO-1234yf
is at least about 70%, more preferably at least about 80% and more
preferably at least about 90%. Preferably before each cycle of use, the
dehydrohalogenation catalyst is dried, pre-treated and activated. It may
also be advantageous in certain embodiments to periodically regenerate
the catalyst after prolonged use while in place in the reactor.
Pre-treatment may include heating the catalyst to about 250° C. to
about 430° C. with a stream of nitrogen or other inert gas. The
catalyst may then be activated by treating it with a stream of HF diluted
with a large excess of nitrogen gas in order to obtain high catalyst
activity. Regeneration of the catalyst may be accomplished by any means
known in the art such as, for example, by passing air or oxygen over the
catalyst at temperatures of from about 100° C. to about
400° C. for from about 1 hour to about 3 days depending on the
size of the reactor.

[0069] While it is possible that the reaction may involve in certain
embodiments a liquid phase reaction, it is contemplated that in preferred
embodiments the dehydrohalogenation reaction comprises, and even more
preferably consists of, at least one vapor phase reaction stage. In one
preferred embodiment of the present invention, the dehydrohalogenation
step comprises a reaction step C having associated therewith at least a
first flow path or feed stream 5A, at least a second flow path or feed
stream 5B and at least a third flow path or feed stream 8, with each flow
path being independently operable. One such embodiment is illustrated
schematically in FIG. 6. In such embodiments, it is preferred that the
first flow path or feed stream 5A comprises HFO-236ea and preferably
substantially all of the HFO-236ea being fed to the reaction step C, the
second path or feed stream 5B comprises HFC-245eb, and preferably
substantially all of the HFO-245eb being fed to the reaction step C (it
being recognized that the feed stream 5B in many embodiments will have a
substantially zero flow). Flow path or stream 8 is at path for allowing
introduction of a recycle stream into the reaction step. In some
embodiments, the actual flow of recycle stream 8 is zero, but in
preferred embodiments, the recycle stream comprises a relatively low
temperature stream comprising a portion of the reaction product stream 6A
after it has been cooled and separated, the content of recycle stream 4,
when present, preferably being relatively rich in HFC-236ea, HFC-245eb,
or a combination of these.

[0070] In another preferred embodiment of the present invention as
illustrated in FIG. 7, the dehydrohalogenation step comprises at least a
first reaction step C1 and a second reaction step C2. The first reaction
step C1, which may comprise one or more reaction stages in parallel or in
series or a combination of parallel or series, having associated
therewith at least a first flow path or feed stream 5A and at least a
second flow path or feed stream 8A, with each flow path being
independently operable. The second reaction step C1, which may comprise
one or more reaction stages in parallel or in series or a combination of
parallel or series, having associated therewith at least a first flow
path or feed stream 5B and at least a second flow path or feed stream 8B,
with each flow path being independently operable. In such embodiments, it
is preferred that the first flow path or feed stream 5A comprises
HFO-236ea and preferably substantially all of the HFO-236ea being fed to
the reaction step C, the second path or feed stream 5B comprises, when
present, HFO-245eb and preferably substantially all of the HFO-245eb
being fed to the reaction step C. Flow path or streams 8A and 8B are flow
paths for allowing introduction of a recycle stream comprising at least a
portion of unreacted feed back into the reaction step. In some
embodiments, the actual flow of recycle streams 8A and 8B are
substantially zero, but in preferred embodiments, the recycle streams
comprises relatively low temperature streams comprising a portion of the
reaction product streams 6A and 6B after they have been cooled and
separated.

[0071] In connection with the reaction stage converting HFO-236ea in the
dehydrohalogenation reactor, it is contemplated that the reaction is such
case proceeds as follows:

CF3CHFCF2H (HFC-236ea-gas)→CF3CF═CHF
(HFC-1225ye-gas)+HF

[0072] It will be appreciated that the present processes may include an
isomerization step to convert to a desirable isomer of HFO-1225ye, which
would typically be carried out at temperatures of about 150° C.

[0073] The second reaction step C2, which may comprise one or more
reaction stages in parallel or in series or a combination of parallel or
series, having associated therewith at least a first flow path or feed
stream 5B and at least a second flow path or feed stream 8B, with each
flow path being independently operable. In such embodiments, it is
preferred that the first flow path or feed stream 5B comprises HFC-245eb,
and preferably substantially all of the HFC-245eb being fed to the
reaction step C. The second path or feed stream 8B comprises recycle of a
portion of the reaction product, as described above.

[0074] In connection with the reaction stage converting HFC-245eb in the
dehydrohalogenation reactor, it is contemplated that the reaction is such
case proceeds as follows:

CF3CHFCFH2 (gas)→CF3CF═CH2+HF

[0075] Preferably, the reaction conditions are controlled in the reaction
in order to achieve the desired conversion and/or selectivity in
accordance with the present invention. As used herein, the term "reaction
conditions" is intended to include the singular and means control of any
one or more processing parameters, including possibly using or not using
a reaction vessel or stage, which can be modified by the operator of the
reaction to produce the conversion and/or selectivity of the feed
material in accordance with the teachings contained herein. By way of
example, but not by way of limitation, conversion of the feed material
may be controlled or regulated by controlling or regulating any one or
more of the following: the temperature of the reaction, the flow rate of
the reactants, the presence of diluent, the amount of catalyst present in
the reaction vessel, the shape and size of the reaction vessel, the
pressure of the reaction, and any one combinations of these and other
process parameters which will be available and known to those skilled in
the art in view of the disclosure contained herein. The size and shape,
and other characteristics of the reaction vessel itself may vary widely
with the scope of the present invention, and it is contemplated that the
vessel associated with each stage may be different than or the same as
the vessel associated with the upstream and downstream reaction stages.
Furthermore, it is contemplated that all reaction stages can occur inside
a single vessel, provided that means and mechanisms necessary to control
conversion are provided. For example, it may be desirable in certain
embodiments to utilize a single tubular reactor for each reaction stage,
providing conversion control by judicious selection of the amount and/or
distribution of catalyst throughout the tubular reactor. In such a case,
it is possible to further control the conversion in different sections of
the same tubular reactor by controlling the amount of heat removed from
or added to different sections of the tubular reactor.

The Dehydrohalogenation Effluent Separation

[0076] As mentioned above, in addition to producing a fluorinated olefin,
preferably fluorinated propene, the dehydrofluorination reaction also
produces HF. In one preferred embodiment, HF is removed from the
dehydrofluorination product stream by countercurrent extraction with
sulfuric acid. In this embodiment, the product stream containing the HF
is fed in one direction to a column, preferably a packed column. At the
same time, a stream of sulfuric acid is fed, preferably countercurrently,
to the same packed column. Appropriate column packing is readily
determinable by one skilled in the art. Suitable column packing materials
include those made of non-metallic polymeric materials, metals and alloys
that are not reactive in the presence of HF or sulfuric acid, such as
PTFE, PFA, hastelloy, monel, and noble metals. Preferably, the stream of
sulfuric acid contains from about 50% to about 100% sulfuric acid, and
more preferably about 80% sulfuric acid. In one embodiment, the stream of
sulfuric acid is continuously fed to the top of the packed column at a
feed rate of about twice the feed rate of the product stream, which in
preferred embodiments is fed from the bottom of the packed column and
moves in an generally upward direction substantially counter currently to
the substantially down flowing stream containing the sulfuric acid. In
certain embodiments, a stream comprising sulfuric acid and HF is removed
from the bottom of the column and preferably at least a portion of the
stream, and most preferably substantially all of the stream, is recycled
back to the extraction tower. The recycling step is repeated preferably
until the HF concentration in the column bottom is greater than about 10%
by weight HF.

[0077] In one embodiment, the sulfuric acid and HF mixture containing
greater than about 10% by weight HF is charged into a separate vessel.
The mixture is then heated to a temperature sufficient to vaporize and
flash off HF, which is collected. Another embodiment includes purifying
the HF collected from the flash distillation.

[0078] Optionally, the HF or HCl generated from the dehydrohalogenation
reaction is scrubbed from the product stream using water or caustic
solutions.

[0079] In certain preferred embodiments, the present invention includes
the step of cooling at least a portion reactor product stream to remove
at least a portion of the heat of reaction. In many preferred
embodiments, this cooling step is included as part of the preferred
aspects of the separation step B, which are described in connection with
FIGS. 4, 5, and 6 below. Preferably the ratio of cooled recycled reaction
product to fresh feed is about 12:1, with the temperature of the recycle
stream preferably being at about 50° C. to about 100° C.,
and even more preferably about 70° C. In addition, in order to
help remove heat of reaction, it is preferred in certain embodiments to
introduce the fresh feeds and/or the recycle feeds to the reaction in the
liquid phase and allowing the heat of reaction to evaporate the liquid
feed and/or the reaction products and withdrawing the reaction products
in the gas phase.

[0080] With reference now to FIG. 8, the reaction product streams 6A and
6B are directed to a separation step D, which comprises in the embodiment
of FIG. 8 a cooling step D1 which produces one or more cooled reaction
product streams 7AB, which in turn are fed to one or more separation
stages D2. It is contemplated that those skilled in the art will be able
to devise without undue experimentation many means and mechanisms for
attaining such cooling in view of the teachings contained herein and all
such means and mechanisms are with the scope of the present invention.
The preferred separation step D2 preferably includes at least a first
separation step which produces a first stream 8 relatively rich in
unreacted fluorinated alkane, such as HFC-236ea and/or HFC-245eb, or a
combination of these, which may be recycled, with or without further
processing, to the reaction step C.

[0081] In one preferred embodiment shown in FIG. 8, the reaction product
7AB is separation step comprises a step for recovering any HF, preferably
as described above, and a step for separating from the crude product
stream unwanted by-product to produce a relatively purified product
stream rich in HFO-1234yf, HFO-1225ye, or a separate stream rich in both.
In certain embodiments, a portion of the HFO-1225ye may be separated from
the product stream and recycled back to the hydrogenation reaction step
and used as a feed thereto.

[0082] In an alternative embodiment, as illustrated in FIG. 9, separate
separation trains may be used for the effluent from the
dehydrohalogenation reaction step, especially when the feeds HFC-236ea
and HFC-245eb are fed substantially separately into separate reaction
trains.